Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753358Ab0DMPxO (ORCPT ); Tue, 13 Apr 2010 11:53:14 -0400 Received: from gir.skynet.ie ([193.1.99.77]:51975 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753178Ab0DMPxM (ORCPT ); Tue, 13 Apr 2010 11:53:12 -0400 Date: Tue, 13 Apr 2010 16:52:53 +0100 From: Mel Gorman To: Minchan Kim Cc: Andrew Morton , KAMEZAWA Hiroyuki , Bob Liu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter Subject: Re: [PATCH 3/6] change alloc function in alloc_slab_page Message-ID: <20100413155253.GD25756@csn.ul.ie> References: <9918f566ab0259356cded31fd1dd80da6cae0c2b.1271171877.git.minchan.kim@gmail.com> <8b348d9cc1ea4960488b193b7e8378876918c0d4.1271171877.git.minchan.kim@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <8b348d9cc1ea4960488b193b7e8378876918c0d4.1271171877.git.minchan.kim@gmail.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1560 Lines: 48 On Wed, Apr 14, 2010 at 12:25:00AM +0900, Minchan Kim wrote: > alloc_slab_page never calls alloc_pages_node with -1. Are you certain? What about __kmalloc -> slab_alloc (passed -1 as a node from __kmalloc) -> __slab_alloc -> new_slab -> allocate_slab -> alloc_slab_page > It means node's validity check is unnecessary. > So we can use alloc_pages_exact_node instead of alloc_pages_node. > It could avoid comparison and branch as 6484eb3e2a81807722 tried. > > Cc: Christoph Lameter > Signed-off-by: Minchan Kim > --- > mm/slub.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index b364844..9984165 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1084,7 +1084,7 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node, > if (node == -1) > return alloc_pages(flags, order); > else > - return alloc_pages_node(node, flags, order); > + return alloc_pages_exact_node(node, flags, order); > } > > static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) > -- > 1.7.0.5 > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/